About 1786 Scottish mechanical engineer Andrew Meikle invented the threshing machine to remove the outer husks from grains of wheat. His machine used fluted rollers to feed sheaves of corn to a rotating drum which beat the corn against a curved casing (the concave). The ears of corn and the chaff then fell through a grating while the straw continued horizontally out of the drum casing.
Before the development of the threshing machine threshing was a very laborious process, done by hand with flails. By the 18th century it occupied about one-quarter of agricultural labor, providing employment to a very large number of workers.